Torcular dural sinus malformation

The dural sinus malformation (DSM) are rare congenital vascular anomalies with variable anatomic features, clinical conditions, and outcomes. There are two forms of disease: a lateral subtype, affecting the jugular bulb with associated high flow arteriovenous fistula; and a midline subtype, called torcular DSM. The torcular subtype is more common and characterized by a giant dural sinus lake involving the confluens sinuum (torcular Herophili). We present a case of a 28-year-old woman with an ultrasound at 32 weeks’ gestation showing a fetal intracranial thrombosed lesion, measuring 6x4 cm. An elective c-section was performed at 38 weeks’ gestation, and a male neonate was born. He remained asymptomatic, and a brain MRI performed 9 days later showed a thrombosed midline mass due to a torcular DSM. The outcome with conservative treatment was favorable, and further development was unremarkable. The 2-year follow-up imaging demonstrated spontaneous involution of the clot. The torcular DSM is frequently diagnosed prenatally as an intraluminar lake thrombosis, and differential diagnosis include tumors, subdural collections, vein of Galen aneurysmal malformations, pial malformations, arachnoid and dermoid cysts. A literature review involving 126 patients with torcular DSM found an overall mortality of 22.1%. Torcular DSM seems to have better prognosis than those having dural arteriovenous shunts, and the worst outcomes were associated to brain damage and patent feeders. In addition, antenatal diagnosis and thrombosis of pouch have good prognosis, possibly because the clot may spontaneously obliterate the fistulas. Treatment options must be individualized, and include conservative, embolization, ventriculoperitoneal shunt and endoscopic third ventriculostomy. Although systemic anticoagulation is controverse in infants, it should be considered for patients with sinovenous thrombosis affecting outflow pathways, especially those aggravated by venous congestion. Intervention is recommended for grade III patients because they progress to grade IV, and endovascular treatment is the gold standard therapy due to the risk of fatal intraoperative exsanguination. Whenever possible, embolization should be prioritized over hydrocephalus treatment because it may avoid ventriculoperitoneal shunt. Close follow-up imaging is recommended to detect any changes, with lesion reduction indicating favorable outcome.

An aberrant venous channel mimicking the perilabyrinthine cells in the petrous bone of a patient with vestibular schwannoma: illustrative case

BACKGROUND Anatomical variations, such as high jugular bulbs and air cell development in the petrosal bone, should be evaluated before surgery. Most bone defects in the internal auditory canal (IAC) posterior wall are observed in the perilabyrinthine cells. An aberrant vascular structure passing through the petrous bone is rare. OBSERVATIONS A 48-year-old man presented with a right ear hearing disturbance. Magnetic resonance imaging revealed a 23-mm contrast-enhancing mass in the right cerebellopontine angle extending into the IAC, consistent with a right vestibular schwannoma. Preoperative bone window computed tomographic scans showed bone defects in the IAC posterior wall, which ran farther posteroinferiorly in the petrous bone, reaching the medial part of the jugular bulb. The tumor was accessed via a lateral suboccipital approach. There was no other major vein in the cerebellomedullary cistern, except for the vein running from the brain stem to the IAC posterior wall. To avoid complications due to venous congestion, the authors did not drill out the IAC posterior wall or remove the tumor in the IAC. LESSONS Several aberrant veins in the petrous bone are primitive head sinus remnants. Although rare, their surgical implication is critical in patients with vestibular schwannomas.

Suprabulbar Approach to Jugular Fossa Tumors: 2-Dimensional Operative Video

Owing to their scarcity, location, and intricate neurovascular associations, jugular fossa tumors are among the most challenging pathologies encountered by the neurosurgeon.1 While paragangliomas originate within and often occlude the jugular bulb, schwannomas and meningiomas are extra-bulbar and typically do not impede venous flow.2 Schwannomas typically arise from an extradural origin, expanding the jugular foramen.3-5 Meningiomas are intradural and cause hyperostosis of the jugular tubercle.6 We described and have been exposing and resecting jugular fossa tumors through a presigmoid suprabulbar infralabyrinthine window6 that has been detailed in cadaveric studies.7,8 This approach maintains the patency of the jugular bulb without breaching the labyrinths or manipulating the facial nerve. It is applicable to cases with partially impaired hearing and intact lower cranial nerves. The carotid artery can be identified by neuronavigation and micro-Doppler ultrasonography. This approach provides a direct lateral trajectory with a short distance to the jugular fossa and cerebellopontine angle. Early exposure and central debulking of the tumor minimize manipulation of the exquisitely sensitive lower cranial nerves. The distal aspect of these tumors can be removed with endoscopic assisted techniques.9 The first patient is a 49-yr-old woman with a previously irradiated schwannoma who presented with worsening neurologic deficits—an extradural suprabulbar approach was used to resect this tumor. The second patient is a 27-yr-old woman with an enlarging meningioma and associated neurological dysfunction; this tumor was resected using the suprabulbar approach with opening of the presigmoid dura. Both patients have consented to surgery and publication of images. Image at 2:27 and 6:38 reprinted from Arnautović et al, with permission from JNSPG. Image at 2:50 and 6:45 ©Ossama Al-Mefty 1997, reused with permission.

Management of jugular bulb injury during retrosigmoid transmeatal resection of vestibular schwannoma

Inadvertent laceration of the jugular bulb is a potentially serious complication of the retrosigmoid transmeatal approach to vestibular schwannomas. Here, the authors present the case of a 51-year-old woman with a right Hannover T4a vestibular schwannoma and bilateral high-riding jugular bulb, which was opened during drilling of the internal auditory canal (IAC). They highlight the immediate management of this complication, technical nuances for closing the defect without occluding the jugular bulb, and modifications of the standard technique needed to continue surgical resection. The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID2155

Endoscopic-assisted resection of vestibular schwannomas in high-riding jugular bulb

The present surgical video demonstrates safe opening of the internal auditory canal (IAC) during vestibular schwannoma surgery via a retrosigmoid approach in the sitting position. Resection of the intrameatal portion of a tumor is important for progression-free survival. Preoperative thin-sliced CT revealed a high-riding jugular bulb obscuring the trajectory. After dural opening, the IAC was approached anteriorly and superiorly. The posterior margin of IAC drilling was above the Tubingen line. Drilling was performed under continuous jugular compression. The vein was pushed down to augment visibility. An angled endoscope was helpful. IAC can be drilled safely in a high-riding jugular bulb with the technique mentioned in the video. The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID2198

Discrepant End-Tidal Concentrations of Sevoflurane at the Same A-Line Autoregressive Index Level during Induction of General Anesthesia: An Observational Study

Background: The A-Line Autoregressive Index (AAI), which is derived from auditory evoked potentials, has been used for determining anesthetic depth. This study verified the correlation between AAI values and the corresponding end-tidal concentrations of sevoflurane during general anesthesia induction. Methods: Thirty young male adults undergoing elective minor orthopedic surgery were sequentially allocated to receive inspiratory 3%, 5%, or 6% sevoflurane for mask induction, followed by mechanical ventilation after tracheal intubation. The inspiratory, end-tidal and estimated jugular bulb concentrations of sevoflurane were recorded at three target AAI values: below 20, below 10, and at the start of burst suppression. Results: The mean time to loss of consciousness in the 6% sevoflurane group was shorter than that in the 5% and 3% groups; however, the groups had comparable AAI values (range: 16–45). The 6% group had a higher end-tidal concentration (4.5% ± 0.2% vs. 3.8% ± 0.2%, p < 0.05) than did the 5% group, despite having the same target anesthetic levels by AAI score ≤10, whereas the estimated jugular bulb concentrations were comparable (1.9% vs. 1.9%) in both groups. Conclusions: Following mechanical ventilation with inspiratory 3%, 5%, or 6% sevoflurane, the end-tidal concentrations were discrepant at the same end points of AAI levels, despite similar estimated jugular bulb concentrations of sevoflurane. Thus, conventional alveolar concentration may overestimate anesthesia depth during rapid wash-in of sevoflurane.

A Transcanal Endoscopic Approach for Management of Pulsatile Tinnitus due to High-Riding Dehiscent Jugular Bulb

Pulsatile tinnitus (PT) caused by a high-riding dehiscence jugular bulb (HDJB) is a rare but treatable otology disease. There are several managements include transcatheter endovascular coil embolization, transvenous stent–assisted coil embolization, or resurfacing the dehiscent bony wall of high jugular bulb under the use of microscope. Among those options, surgical resurfacing of HDJB might be an effective and safe choice with less destruction. However, previous studies approached middle ear cavity via microscope can only provide a lateral, indirect view, while resurfacing the vessel through a transcanal endoscopic ear surgery (TEES) approach may give surgeon a direct and easy way to manage HDJB. In this report, we presented a case of 40-year-old woman with HDJB and shared our clinical consideration and reasoning of the surgical management of PT via a transtympanic approach by TEES rather than a transmastoid approach.

Somatosound: A review with report of 9 cases with long-term follow-up

Somatosound (somatic tinnitus) is associated with vascular, musculoskeletal, respiratory, or temporomandibular joint disorders. Several studies of its management have been widely reported, but only few presented long-term follow-up results. The purposes of this paper are to review the causes and management, present cases with long-term follow-up, together with previously reported cases in literatures. We treated nine patients with somatosound of vascular, hematologic, endocrinologic, muscular, and cervical origin. Follow-up were conducted routinely, and the final results were collated in 3 to 11 years. Patients with non-life-threatening causes were given counseling and palliative management. Their tinnitus becomes tolerable, gradually decreased, and even disappeared. Patients with life-threatening causes were treated immediately. Among all, there were three cases which to the best of our knowledge, are the first reported of its causes. One case was caused by a compensatory of increasing blood flow in internal carotid artery (ICA) secondary to contralateral ICA stenosis. Another had a combination of anemia and an ipsilateral jugular bulb diverticulum. The tinnitus disappeared after the anemia treated. The last was patient with hyperthyroidism. The tinnitus disappeared by controlling the condition. Even when the causes are benign and the available treatments may carry risks, the patients should not be left unmanaged. Symptomatic treatment should be given, such as counseling, sound therapy, and palliative management. Our long-term observation indicated that overall outcomes are positive when the etiologies are identified early and managed properly.